The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the inventors hereof, to the extent the work is described in this background section, as well as aspects of the description that does not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted to be prior art against the present disclosure.
A wireless digital communication system typically includes a transmitter that converts digital data samples into an analog signal, which in turn is modulated or encoded onto a carrier signal for transmission via a wireless channel to a receiver. The receiver receives an analog signal from the wireless channel, and recovers the transmitted data samples from the received signal, i.e., by demodulating or decoding the received analog signal and converting the analog signal to digital samples. In order to recover the transmitted data samples from a received signal, channel state information that is indicative of a combined effect of scattering, fading and power decay with distance to the transmitted signal is usually needed. Conventional systems typically use a training sequence, whose sequence composition is known to the receiver such that the receiver can generate the channel state information by comparing the recovered data sequence from the received signal and the known training sequence. The generation of the channel state information based on transmitting a training sequence is usually performed before transmitting any payload data. Thus, when the channel varies over time, the training sequence needs to be re-transmitted periodically, or intermittently to re-calibrate the channel at the receiver. The periodic channel re-calibration with training sequences usually causes transmission latency for the payload data, and also negatively affects the network throughput performance.